Conventional PEM fuel cells may employ a water management system which includes porous water transport plates which have reactant gas on one side and water on the other side. Such systems generally include a water pump, and an accumulator, together with a gas separator which is required for effective pumping with low cost pumps. The accumulator takes up space which is scarce, particularly in electric vehicles powered by a fuel cell. Furthermore, the parasitic power requirement of the electric pump detracts from the overall efficiency of the fuel cell process.
Furthermore, when a PEM fuel cell is to be utilized in environments in which the cell stack may fall below the freezing temperature of water, the removal of water at shutdown is a requirement, which is mitigated if less water has to be removed. Additionally, startup in such a system with a frozen pump and conduits can be extremely difficult if not impossible.